With respect to a turbine blade of a gas turbine, the load per one blade tends to increase by considering cost reduction and the like by reduction of the number of pieces of the blade. In a blade to which a large load is applied, a flow in a cross section perpendicular to a flow of a mainstream gas: i.e. a secondary flow increases in the vicinity of an end wall. Because the secondary flow increases, the flow rate in the vicinity of the end wall reduces, and, by the portion, the flow rate in the vicinity of the average of the radial position on the outer periphery side and the inner periphery side: i.e. the average diameter of the blade increases, and the blade load increases. It is known that the increase of the total pressure loss is caused as a result of it.
A method has been disclosed in which the shape of the end wall surface is made a non-axisymmetrical shape in order to cope with the increase of the total pressure loss in a blade having a large blade load. As an example, a blade has been disclosed in PTL-1 in which a curved surface having a pair of a convex surface on the pressure surface side and a concave surface on the negative pressure surface side is formed in the end wall surface.
A blade has been disclosed in PTL-2 in which a convex region is arranged in the end wall so as to be uniform in the rotation direction: i.e. rotationally symmetric.